Various methods are known for measuring the cure of resinous materials. For example, colorimetry, spectroscopy and torsional braid analysis provide thermal, chemical and mechanical analyses of resins; however, these techniques are laboratory tests and are not suitable for on-line production monitoring. Dielectrometry, i.e. metal foils imbedded in parts during manufacture and excited by A.C. currents in the range of 100 Hz to 100 kHz, provides for on-line testing, but results, to date, have failed to provide reliable cure monitoring data.
There exists a need for a reliable, inexpensive, resin cure monitor which is sensitive to the test material's dielectric property changes and which can be implanted during manufacture and be suitable for on-line testing. Preferably the apparatus should also be adaptable to measure other properties of the test materials, such as moisture content, as well. Attention is directed to a master's thesis by S. L. Gaverick, an inventor herein, entitled "A.C. Measurements with a Depletion-Mode Charge-Flow Transistor" submitted to Massachusetts Institute of Technology in September, 1980, incorporated herein by reference.